1. Field of the Invention
The present disclosure generally relates to a charge pump and a dynamic charge pump device including the same, and more particularly to a charge pump including a plurality of voltage sources, in which an output voltage of the charge pump may be compensated by switching between the plurality of voltage sources of the charge pump, and a voltage of a power source or a ground source of an external load circuit may be adjusted according to a variation of the output voltage of the charge pump.
2. Description of Related Art
A charge pump is a commonly used circuit structure capable of multiplying an input voltage to a high voltage through combinations of transistors and capacitors.
FIGS. 1A-1C are operational schematic diagrams of a conventional charge pump (CP).
The CP may generate a new voltage by utilizing a voltage source with a predetermined voltage and the principle that capacitors are capable of storing electric charges. The new voltage may be positive or negative. In FIG. 1A, first to a fourth switches S1-S4, a first capacitor C1, and a second capacitor C2 are arranged. The first voltage source V1 is connected to a first end of the first capacitor C1 through the first switch S1, the second voltage source V2 is connected to a second end of the first capacitor C1 through the second switch S2, and the first capacitor C1 and the second capacitor C2 are connected in parallel through the switches S3 and S4, respectively.
FIG. 1B illustrates a first operating phase (Phase 1) of CP, in which the first switch S1 and the second switch S2 are turned on, the third switch S3 and the fourth switch S4 are turned off, the first capacitor C1 is charged by both the first voltage source V1 and the second voltage source V2. FIG. 1C illustrates a second operating phase (Phase 2) of CP, in which the third switch S3 and the fourth switch S4 are turned on, the first switch S1 and the second switch S2 are turned off, the electric charges stored in the first capacitor C1 during the Phase 1 is distributed to the first capacitor C1 and the second capacitor C2.
After repeating Phase 1 and Phase 2 for several times, the capacitor C2 can be sufficiently charged, and a voltage V4(V3) different from the voltage V3(V4) may be obtained according to the initial voltage of the voltage source given to the voltage V3(V4). The voltages V3 and V4 can be positive or negative.
In application, the charge pump CP of FIGS. 1A-1C may be connected to a voltage source VDD at one end, and an output terminal of the charge pump CP is connected to a power supply terminal Vcp of a load circuit LC between an input terminal Vin and an output terminal Vout, as the charge pump CP shown in FIG. 1D. A load RL may draw current from the charge pump CP through the supply terminal Vcp when needed to maintain the stability of the load circuit LC, and different voltage drops at the supply terminal Vcp may generate according to the demand of the load circuit LC.
However, when the load RL demands a large amount of current, the load circuit LC may experience a large voltage drop. Under such a circumstance, the charge pump CP may not be able to supply enough output voltage to maintain the stability of the load circuit LC because the output voltage of the charge pump CP are not sufficient. The voltage at the supply terminal Vcp may drop affecting the efficiency of the load circuit LC, such as an increase of the total harmonic distortion (THD).